Fuel pump



BEACH/AM mi. Puur Oct. 12, 1948.

s sneetksnutl Filed May 9, y.1944

Oct. 12, 1948. i'. E. BEACHAM FUEL PUMP 3 Sheets-Sheet 2 Filed May 9. 1944 Oct. l2, 1948'. 1'. E. aEAcHAM rum. PUMP :sr shuts-sheet :s 7

Filed lay 9, 1944 'a small part being Patented Oct. 12, 1948 NT OFFICE FUEL PUMP Thomas Edward Beecham, London, England Application May 9', 1944, Serial In Great Britain March 8, 1943 seuuuu 1, rubuu Law 69o, August s, 194s Patent expires March 8, 1963 '7 claims. (ci. ros-5) This invention relates to fuel pumps, and has particular reference to fuel pumps for supplying the fuel to internal combustion engines. Fuel pumps for this purpose are known,A in which. in addition to the main pump, an impeller is p rovided for the purpose of creating a difference of pressure which bears a definite relationship to the speed of the pump and engine, which pressure operates through suitable control mechanism to regulate the ,now of fuel from the main pump to the engine in such a way as to provide the required relationship between the quantity of fuel supplied and the engine speed.

The object of the invention is the provision of an improved layout of this character, and the invention consists broadly in the arrangement that the main pump (in conjunction with which the impeller is employed) takes the form of a gear pump. The invention also comprises the provision of a self-contained safety valve in the one casing with the pump.

In order that the invention may be the more clearly understood, a construction in accordance therewith will now be described, reference being made-to theaccompanying drawings, wherein:

Figure 1 is a side elevation of said construction, shown mainly in section on line I-I of Figure 2, in section on line I-I of Figure 3;

Figure 2 is an end elevation of the same looking from the left of Figure l'with certain of the parts at the left hand end partly broken away;

Figure 3 is an end elevation of the same looking from the right of Figurel 1, shown mostly in section on line III- III of Figure 1;

Figure 4 is a sectional plan taken on line IV-IV of Figure 1.

Referring to these drawings the construction comprises a main pump of the gear type for pumping the fuel to the engine (not shown) said pump comprising a single pair of`gear wheels I and 2 and having inlet and outlet conduits 3 and 4 respectively. The gear wheel I is mounted on a main shaft 5 which -ris driven from the engine, and the gear Wheel 2 is an idler gear which rotates on a short fixed shaft 6. In addition to the main pump I, 2 I provide, on the shaft 5, an auxiliary impeller I acting to produce centrifugally a difference between the uid pressures of two annular spaces 3 and 9, which difference is proportional to the square of the speed of the pump and therefore of the engine. The fluid pressures in said spaces 8 and 9 are applied, through respective conduits I0 and II, to a suitable control mechanism (not shown) which responds to the lbe hereinafter explained, with the the low pressure space 9 2 differences in said -fluid pressures so as to regulate the flow of fuel from the main pump I, 2 toprovide the The lower pressure space 9 is therefore at a pressure which is lower than the pump pressure by an amount depending on the speed ofthe pump and engine. A slow reverse flow oi' fuel through the impeller is provided for by providing a restricted leakage path, as will hereinafter appear, from the lower pressure region of said impeller to the low pressure side of the main pump. This leakage path comprises an orifice whose size can be adjusted to provide for any desired rate of leakage ilow.

The auxiliary impeller 'I is of the type, as'will be clear from the drawing, comprising vanes in A straight radial planes containing the axis. Saidv vanes rotate in an annular chamber which fits close to the side edges of the vanes. 'I'his annular chamber on one side (in practice the side away from the gear pump I, 2) communicates, as will aforesaid two annular spaces/L8 and 9. These spaces are, as shown, coplanar and concentric with the impeller, and the high pressure space 8 is at a radius about equal to that of the tips of the vanes, while greater than that of the roots of the vanes.

' The pump I, 2 is provided with a self-contained safety valve adapted, should the load become too high, to open and connect the pressure conduit 4 to the suction conduit 3. This safety valve, which is shown in Figure 4, comprises a' discshaped valve element consisting of two parts I2 and I3 divided in the mid piane of the disc, which valve element I 2, I3 is biased 'by means of a spring Iso that its part I2 seats on a circumferential ledge I 5 on the inner periphery of a hole I6 which, on the seating side of said valve element I2, I3, is connected to the pressure conduit 4, and, on the other side of said valve element I2, I3, is connected to the suction conduit 3. Thus when the pressure on the pressure side of the pump exceeds a given amount, the valve element I2, I3 is lifted from the circumferential ledge I5, and the liquid flows from the pressure conduit 4 to the suction conduit 3.

In order that this valve shall not be influenced by the pressure on the suction side'of the pump, the valve element I2, I3 is connected by means of an axial strut I1, to a flexible diaphragm I8 is at a radius ratherP f suction conduit 3.

I- phragm I8.

element and diaphragm on which this pressure v acts are made equal, and thus the total effect upon the valve of the pressure of the suction side of the pump is zero. Beyond the diaphragm I3, a

cap I9 is ntted on the end of said hole I3, which cap is ntted with a pipe connection 20. It is clear that by varying the pressure within the cap I3` thatis the pressure on the outer side of the diaphragm I8, the pump pressure at which the valve I3, I3 will respond can be varied without any ad- Justment being made to the biasing spring I4. In practice a pipe from this cap I3 leads to the inlet of the engine supercharger, whose pressure may be above or below atmospheric. Thus the safety valve is automatically set to respond to a given pump pressure depending upon the pressure of the supercharger inlet.

In the construction of this safety valve, the circumferential ledge I is formed on an integral end piece 2| which rlts accurately into the end of the hole I3 beyond the pressure conduit 4. The outer end of this end piece 2| is flanged as shown diaphragm I1 being clamped between said member and cap.

The connections between the conduits 3 and 4 and the hole I3 are permanently established, as

` shown, but all the parts within saidl hole I6, from the end piece 2| to the cap I3, can be reversed with respect t'o said hole from end to end, so that the safety valve can still be used if it is desired to reversethe direction of operation of the pump and make the conduit 3 the pressure conduit and the conduit 4 the suction conduit.

.In construction. the chamber for the pump gears I and 2 is constituted by a main block 30 and an end block 3| bolted with two adjacent faces. at right angles to the pump shaft, together,

the face of the main block being recessed to provide said pump chamber. The conduits 3 and 4 which pass to and from said chamber `are formed wholly within said main block 30, and the hole I6 is accordingly also formed wholly within said main block. Assuming that the construction is orientated, as shown. with the shaft horizontal and the gear I vertically above the gear 2, said conduits 3 and 4 run parallel upwardly to the appropriate sides ot the gear chamber, and said hole' I3 is horizontal, running transversely through said main block 30 and cutting at one side into so as to form a complete closure for that end of the hole. The inner end of said end piece 2| extends to a point between the pressure conduit 4 and the suction conduit 3 and is hollowed and.

fits closely in said hole I6 as shown so as to form the said 'circumferential ledge. 'I'he intermediate part of said piece 2| is waisted as shown 'so as to form an annular space to which the ypressure in the conduit 4 has accessand is provided with holes 22 to admit said pressure to the appropriate face of the part I2 of the valve element I2, |3.

The part4 I2 of the valve element is formed with an axial projection 23 which 'engages slidingly vided with holes 25 by which access is given from the suction conduit 3 to said diaphragm. The strut l1 is formed with a flange 26 which is engagedby said part I3 to press the aforesaid end of said strut into the axial recess in the part I2,

, and the dimensions are such that the extremity of said strut engages the end of said axial recess so as"to press said part I2 against the circumferential ledge I5 while maintaining the two parts I2 and I3 slightly spaced from each other. Holes 21 are provided in the part I2 which holes are normally kept closed by means of a closing disc 23'pressed down on to the high pressure side of said part I2 by means of a light coil spring 23 `in compression between said closing disc and the end piece 2|. It will thus be seen that, should thepump be inadvertently reversed so that the conduit 3 becomes the pressure conduit and the conduit 4 the suction conduit, the liquid can flow straightfrom the conduit 3, between thevalve parts I3 and I2 and through the holes 21 to the conduit 4. Y

As will be seen the member 24 is clamped between the-end of the hole I3 and the cap I3, the

I 8, said member 24 forming a bearing for the strut I1 and being pro- 'in a corresponding axial recess in the end piece Y said conduits 3 and 4 as shown to establish communication with them.

Suit-able recesses are also` formed in the main block 30 and end block 3| to receive two ends of the fixed shaft 3 for the idler gear`2.

The pump shaft 5 passes through both blocks 30 and 3|. Said shaft is provided with two plain journal bearings, one located between the gear I and the impeller 1, and the other located on the side of said gear I remote from said impeller. The rst of these Journal bearings consists of a steel sleeve 32 fixed on said shaft 5, running in a bronze bush 33 fixed in the main block 30. The other Journal bearing is formed by an enlarged portion of the shaft 5 running in a bronze bush 34 fixed in the end block 3|.

y:bearing element 35 fixed as shown to the end of the main block 30 remote from the gear, and

engaged by a steel disc 33 mounted on the shaft at a position Just beyond the said end of said main block. Said bearing element 35 may comprise bronze or graphite and the arrangement is such that the end thrust bearing keeps the two faces of the gear I Just clear of the adjacent faces of the gear chamber.

The closely tting'chamber for the impeller 1l together with the two annular spaces B and 9 communicating with said chamber, are constituted in the following way:

A disc-shaped plate 31, whichis dished as shown to accommodate 4 the steel disc 36, is clamped between the end of the main block 30 and a cap-shaped part 33. f The shaft 5 passesv through the disc-shaped plate 31 and into the space formed between it and the cap-shaped part 33. The varies of the impeller 1 are mounted on the shaft 5 close to the disc-shaped plate 31. The cap-shaped part 33 is formed with a hub 33 surrounding the end of the shaft on the other side of the vanes. and, around this hub, said capT shaped part 38 is formed with an annular recess facing the vanes, in which is bolted, by means of bolts 40a, and aligned by means of a suitable 4 regulator, a T section ring 40, arranged as shown ,5' a that its cross flange is close and parallel to the edges of the vanes and nearly` cuts of! the annular space from` the` vanes, and its centre i ilang/e divides said yannular space into the two separate annular spaces 8 and 9. It will be seen that these two spaces 8 and 9 communicate with the closely fitting chamber in which theimpeller rotates, respectively by way of a narrow annular clearance between the outer edge of the ring 40 and the inner periphery of the cap-shaped part 38 and by Way` of a narrow annular clearance between the inner edge of the ring 40 and the outer periphery oi the hub 39. The aforesaid conduits I and, leading spaces 8 and 9 pass through the cap-shaped parts 38 and are adapted to be connected to suitable pipes. The said annular'spaces and 9 have the function of destroying the circumferential velocity 'of the liquid and preventing this from being converted into static head.

The shaft at its end remote from the im peller 1 is provided with liquid seals to prevent leakage of liquid. Thus the end block 3| is hollowed, as shown, having a cylindrical axial recess in its end remote from the main block, into wlich recess the shaft 5 passes. The aforesaid bearing bush 34 is ilxed in this recess at the end thereof nearest the main block 30. Secured in said recess next to said bearing' bush 64 is' a ring 4|, which ring 4| is sealed with respect to the inner periphery of said cylindrical recess, by means of a ring of sealing material 42., A cylindrical part 43 is screwed into the end of said recess and sealed with respect to the inner periphery of said recess by means of an annular sealing disc 44. The extermity of the shaft proper 5 lies within said ring 4| and said shaft is coupled to a splined spigot 45 lying-just outside the end block 3| by means of a so-called Oldham coupling which affords a hermetic seal both against said ring 4| and the cylindrical part 43. The splined spigot 45 is for coupling the shaft to the engine.

Thus said Oldhamcoupling comprises parts 46 and 41 coaxial withthe adjacent the end` of said Yshaft and having a diametrical tongue which engages' a diametrical slot in the end of said shaft, and the part 41 being on the side oi the part 46 remote from said shaft and having a diametrical tongue which engages with a diametrical slot in said part 46. The two diametrical slot and tongue connections are at right angles to each other as shown. The parts 46 and 41 are formed with respective flanges 48 and 49, and said parts are biased axially away from one another by means of a coil spring 50 in compression between said flanges and thereby said flanges are biased against respective sealing rings 5| and 52 mounted' on the ring 4| and the cylindrical part 43 as will be clear from the drawings.l As shown the spigot 45 is rigid on the part 41.

The fixed shaft 6 on which the idler gear rotatesis provided, mid way along its bearing portion. with either a circumferential groove or a ring of circumferential holes 53 communicating with a hole 54 extending axially of said shaft to one end and leading to a passage 55 which communicates with the hole I6 at a point of the latter which is always connected to suction whichever the direction of Thus fuel will leak from the gear chamber, through the clearance between each face of the idler gear 2 and the adjacent face of said gear chamber between said gear 2 and the fixed shaft shaft, the part 46 being operation of the pump.

from said annular 6 and through the passages the suction side of the pump. Thus a lflow of liquid is -provlded through the ,bearing ofthe gear' 2 which ensures that it shall 'runwitl 1' `a `reasonably small amount of wear'. l v\ As the hydraulic pressures at the .twd endsof the bearing bush 33 may be nearly` equal ,at`slo speeds, said bush mid way along its bearing portion. is preferably providedxwith.. a circum'fv ferential groove or a circumferentialgring of holes 56 which communicate by way of a passag'e'jl with the said passage 55, so thata flow. of fl through the bearing 3 3 from both endswill takfe place. To enable the fuel to reach the left hand end of the bearing 33, the right hand face of thc disc 36 is.v formed with shallow radialv grooves. This also ensures lubrication of the end thrust bearing.

y It will be seen by reference to Figures 1 and 3 former to the latter,

that the low pressure side of the gear pump is in communication, by way of aconduit 58, with a transverse conduit 59 from which extends a longitudinal conduit 60. The conduit 6U is therefore at the pressure of the suction side of the pump. The aforesaid leakage path from the low pressure region of the impeller 'i to the suction side oi the pump' goes to this conduit 60 by way of a narrow annular clearance 6| at the inner edge of the dished plate 31 leading to the space 62 on the right hand side of said dished plate, froz which space passages 63 and 64 lead to said conduit 60. An adjustable valve 65 regulates the rate of leakage through this path as will be clear from the drawing.. i

The trapped space on the right hand side of the bearing bush 34 is also connected to this conduit 60, by way of passages 66 and 61. so that undue pressure shall not be applied to"the seals at 42 and 5|.

Itwill be seen that a conduit 68 is provided leading from the conduit 59 to the high pressure side of the pump,but that this conduit '68 is closed by means of ever the direction of operation of the pump is to be reversed, this valve 69 will be exchanged with a plug 10, so that it will now close the conduit 58 and the conduit 68 will be open. Therefore, as will be clear from the drawing. the conduit 5 9 will still be connected to the suction side of the pump, now on the right of Ffigure 3, and cut oi from the pressure side, now on the left.

Other constructional details are deemed sufflciently clear from the drawings.

What claim and desire to secure by Letters Patent is: i

1. A fuel pump for an internal combustion engine comprising a gear nected to, and driven by the internal combustion engine. at a speed corresponding to the engine speed and having inlet and Aoutlet conduits adapted `to be connected respectivelyto a fuel supply and said engine to deliver fuel frcm'the an impeller coupled to thc gear pump and driven ing speed, a highV pressure chamber connected with the discharge of said impeller, ia low bressure chamber connected with the intake of the impeller, a pressure responsive means connected between said high and low pressure chambers and means associated with said pressure responsive means for varying the flow of fuel from said 5a, 54 and 4als, -to

a valve 69 as shown. Ii' howpump adapted to be com therewith at a correspond- L positioned between i 7 l 3. A iuelpump as dened in claim 1 in which the high pressure chamber is in full communica- Vtion with the high pressure side o1 the gear pump and the low pressure chamber communicates with the low-pressure side of the gear pump through a leakage path.

4.' A fuel pump as deilned in claim 1 in which the high pressure chamber is in full communication with the high 'pressure side of the gear pump and the low pressure chamber communicates with the low pressure side of the gear pump through an y:adjustable leakage path.

' 5. A fue1 pump as defined 1n claim 1 in which vthe impeller comprises radial vanes enclosed within an annular impeller chamber, the high pressure chamber is an annular chamber coaxial with thedmpeller chamber and communicates therewith adjacent the tips ,of the radial varies and the low pressure chamber is an annular chamber coaxial with the impeller chamber and communicates therewith adjacent the roots of the radial vanes.

6. A fuel pmp as dened in claim 1 in which the impeller comprises radial vanes enclosed with- .in an annular impeller chamber and the high pressure and low pressure .chambers are annular chambers coaxial with said annular impeller chamber, said impeller chamber and said annular high and low pressure chambers being separated from each other by an annular member of T-shaped cross section having its cross ilange adjacent to the radial vanes and its center ange the high pressure chamber -and the low pressure chamber, there being clear- Iances between the inner and outer edges o! said cross flange and the adjacent walls o! said chambers providing communication between the impeller chamber and said high and lowlpressure chambers.

'1. A fuel pump as defined in claim 1 comprising a safety valve connected between said inlet and outlet conduits, said safety valve comprising a symmetrical cylindrical chamber, closure means for both ends of said cylindrical chamber and valve means and valve biasing means supported between said closure means, said closure means and the valve and valve biasing means being reversible with respect to said cylindrical chamber.

.THOMAS EDWARD BEACHAM. REFERENCES crran The Qfollowing references are of record in the file of thi/s patent:

Oct. 20, 1942 

